Methods for detection and prevention of monocular and binocular visual impairment in childhood

The main causes for monocular visual loss in childhood are amblyopia and injury, and in the case of poor vision in both eyes refractive errors, the principle cause being myopia. Reliable visual acuity testing, reaching children at as young an age as possible, is essential in detecting these conditions and monitoring their treatment.

Visual acuity: Two methods to measure Snellen equivalent visual acuity in children aged 18 months and upwards are described, the Kolt-test and the O-test, both designed by the author. The validity of both tests has been evaluated.

Visual development: Results on normal visual development in healthy eyes, measured with either of these tests are presented here. Separate visual acuity measurements were taken for both eyes of 89 Swedish children aged from 24 months to 4 years. The mean visual acuity was 0.48 at 24 to 29 months; 0.55 at 30 to 35 months; 0.67 at 36 to 41 months; 0.77 at 3 1/2 to 4 years.

Prevalence of amblyopia, myopia and injury: A nation-wide eye survey in 6292 school children in the Sultanate of Oman from Grade 1 (6 to 7-year-olds) and Grade 6 (11 to 12-year-olds) was conducted. Screening of visual acuity was done using the Kolt-test in Grade I and linear E in Grade 6. Amblyopia was found in 0.92%, strabismic amblyopia in 0.48% and anisometropic amblyopia in 0.45%.

There was statistically significant more strabismic amblyopia in I I to 12-year-olds when compared with the 6 to 7-year-olds. Myopia (>=-1.0) was present in 0.56% of the 6 to 7-year-olds. The sample including I I to 12-year-olds showed that an average of 5.16% were myopic. The findings showed significantly less myopia in remote areas. Monocular traumatic visual damage was found in 0.21% of the 6292 children.

Amblyopia treatment results: Forty-four Swedish children aged 2 to 9 years with amblyopia were prospectively followed up during treatment. Compliance with treatment was the most critical factor predicting a successful outcome. Among the compliant children 35 out of 36 (age 2 to 7 years) were cured within 100 days regardless of diagnosis, degree of amblyopia and age.